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All Journal Journal of Mathematical and Fundamental Sciences INDONESIAN JOURNAL OF APPLIED PHYSICS
Sorja Koesuma
Department of Physics, Sebelas Maret University, Surakarta
Astronomy Chemistry Earth & Planetary Sciences Energy Materials Science & Nanotechnology Mathematics Physics

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Preliminary Estimation of Engineering Bedrock Depths from Microtremor Array Measurements in Solo, Central Java, Indonesia Sorja Koesuma; Mohamad Ridwan; Andri Dian Nugraha; Sri Widiyantoro; Yoichi Fukuda
Journal of Mathematical and Fundamental Sciences Vol. 49 No. 3 (2017)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2017.49.3.8

Abstract

In the last decade the city of Solo, located in Central Java, Indonesia, has grown significantly and become a major city. Many industries and hotels have been built in the city and its surroundings. This study aimed to determine the engineering bedrock depths in Solo, an important parameter in seismic hazard analysis. The microtremor array method was used to obtain 1D S-wave velocity profiles and construct layer depth maps. The spatial autocorrelation (SPAC) method was used to calculate the dispersion curves, while the S-wave velocity structure was derived using a genetic algorithm (GA). The results of the S-wave velocity structure in Solo show that there are four stratigraphic layers, where the engineering bedrock depths in Solo exist within the range from 145 to 185 m. The shape of the bedrock basin is elongated in an east-west direction.
Utilization of Satellite Gravimetric Data to Estimate the Location of the Magma Chamber of Slamet Volcano, Central Java, Indonesia Sehah Sehah; Sorja Koesuma; Urip Nur Wijayanto Prabowo; Aina Zahra Ikhwana
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 13, No 2 (2023): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v13i2.73923

Abstract

Satellite gravimetric data can be utilized to map the gravity anomaly on the earth's surface, especially for difficult, extreme, and large areas. In this study, satellite gravimetric data has been used to estimate the location of the magma chamber of Slamet volcano, Indonesia. Information on the magma chamber is very useful for knowing the volcanic characteristics and activity, thus helping pre-mitigation efforts to catastrophic eruptions that occur. The stages in the study which have been carried out include data access, correction, reduction, modeling, and interpretation. The satellite gravimetric data that has been accessed is GGMplus data. After several corrections and reductions are done, the complete Bouguer anomalies (CBA) data are obtained with values ranging from 11.889 – 117.429 mGal. Filtering process using the upward continuation has been applied to obtain regional anomalies data. The regional anomalies data are corrected to the CBA data, so that the residual gravity anomalies data are obtained. The lowest gravity anomaly value is located at positions of 109.21967 E and 7.24281 S which is interpreted to be the location of the magma chamber of Slamet Volcano that is currently still active. The result of modeling of the residual gravity anomalies data indicate that the position of the magma chamber of Slamet Volcano is estimated to be relatively under the cone with a density lower than the surrounding rock densities, i.e. 1.50 – 1.75 g/cm3. The study results have a good match with the geological map of the study area.
Co-Authors Aina Zahra Ikhwana Andri Dian Nugraha Mohamad Ridwan Sehah Sehah Sri Widiyantoro Urip Nur Wijayanto Prabowo Yoichi Fukuda